Yes it will apply to plumbers.
Yes it will apply to DIY.
Yes it will apply to anybody doing anything except very minor alterations.
Yes it will apply to anybody, doing anything at all - even replacing a light switch - in a "special location", which includes kitchens.
So plumbers will not be allowed to, for instance, put in a spur to provide power for a boiler.
To be fair - it's not so much that all the above will be forbidden, but they will all become controlled work under building regs, and unless carried out by someone deemed to be competent to self-certify their work, will have to be notified to building control before work starts, and must be inspected and tested by them, or someone they designate. i.e. your local NICEIC etc registered firm who, as il78 points out, have had these new regulations brought in so that they can boost the earnings of their members.
And in case you're spluttering about not being able to wire up a boiler any more, perhaps you should have a word with the guy who installed mine and spurred a length of unfused 1.0 or 1.5mm flex from a socket to provide the power for it. Can't tell what sort of flex- O/D is approx 7-8mm, which probably means 1.5mm, but who knows?
He did put in a fused spur connection unit, but that was just before the flex went into the boiler, thus leaving me with around 3m of 1.0/1.5mm cable rated at 10/16A, between that and the socket, on a circuit protected by a 32A MCB.....